My 2 door is the same. That is where the seatbelt attaches and they are not threaded. We do have threaded inserts on the sides of roll cage that would work if the top was off. I don't know if 4 doors have those.
Lights are easy if you have the aux wire running to the rear. I recommend getting a 12 v connector and testing where you want them. I bent a couple little metal brackets from the hardware store and mounted to the bolt at the bottom of the speaker. It was easy to run the wires. I think I...